Fuse terminal clip



Nov. 29, 1966 A. BACHMAN 3,289,144

FUSE TERMINAL CLIP Filed March 5. 1965 lNVENTOR m. n.

ANATOLE BACHMAN BY 4240 F4a ATTORNEY United States Patent O 3,289,144 FUSE TERMINAL CH1 Anatole Bachman, Willowdale, Qntario, (Janatla, assignmto Federal Pacific Electric Company, Newark, Null, a corporation of Delaware Filed Mar. 5, 1965, Ser. No. 437,415 9 Claims. (Cl. 339149) This invention relates to improvements in fuse terminal clips for releasably holding and electrically engaging the terminal of an electrical fuse.

Fuses are widely used in electrical power distribution equipment for the protection of circuitry as well as the protection of the connected devices. Low voltage equipments, designated'as fusible equipment, generally employ fuses that may be rated up to 600 volts A.C. with the current capacity selected to match the current rating of the wiring or device. Fusible equipment, such as fusible safety switches, is designed to accept a range of fuses of different current capacity up to the rated current of the switch. Typically a 100 ampere switch is provided with fuse clips which will accept 70, 80, 90 and 100 ampere fuses. Fuses above 65 amperes are generally provided with knife blade terminals and it is with fuse clips for such terminals that the present invention is concerned.

It is an object of this invention to provide a fuse clip comprising relatively few component parts which will serve to firmly hold the fuse terminal in good electrical engagement.

It is another object of this invention to provide a fuse clip in which the fuse terminal engaging members provide firm engagement with the terminals of the fuse inserted therebetween.

It is yet another object of this invention to provide a fuse terminal clip capable of receiving the blade terminals of a wide range of fuse sizes.

Another object is to provide a fuse terminal clip which is highly reliable and yet simple to assemble.

The foregoing and other objects an advantages of the invention are achieved in one embodiment of the invention by the provision of a fuse terminal clip having a resilient member that is urged into engagement with the knife blade fuse terminal and the fuse terminal receiving surface of the clip contact member. The knife blade fuse terminal is guided by and received between the resilient member and the contact member. The bias member supplies the requisite contact pressure between the contact member and the fuse terminal.

For a better understanding of the invention, reference is made to the following description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a plan view of a fuse terminal clip constructed inaccordance with the invention with a fuse shown in engagement therewith;

FIG. 2 is a greatly enlarged elevation view with some parts in section taken along the line 22 of FIG. 1;

FIG. 3 is a plan view of an insulating base member which forms a part of the fuse terminal clip; and

FIG. 4 is an elevational view of the J-shaped resilient member,

Referring to the drawings, there is shown a fuse terminal clip 19 which is adapted to engage a knife blade terminal 12 of a cartridge-type fuse 14. A similar clip or other suitable means, not shown, is used at the other end of the fuse to complete the circuit through the fuse. For an example of such other means see my copending application entitled Circuit Interrupters, Serial No. 394,521 filed September 4, 1964, which is assigned to the same assignee as the present invention wherein the fuse terminal clip forms part of the interrupter structure. The clip includes four basic members; an insulator base 16, a base plate 18, an L-shaped fuse blade contact- 3,289,144 Patented Nov. 29, 1965 ing member 20, and a J-shaped contact pressure or bias member 22. Each of these members will be described in detail below.

The insulator base 16 is formed of a molded block of high impact strength bakelite or other electrically insulating material having suitable mechanical and electrical properties. The upper surface 24 of the base has a raised area 26 thereon which has a flat top surface 28. A recess 3t), defined by end walls 32, 34, opposed side walls 36, 38 and a bottom wall 40, is formed in the base and extends into both the surface 24 and the raised area 28. An appropriate aperture 42 is provided for the base mounting screw, not shown. Additional apertures 44 are provided for screws 46 which secure the base plate 18 to the base. These screws are threaded into plate 18 from beneath the base 16 and thereby relieve the material of the base from the necessity of retaining the screws by thread engagement. A multipole fuse block may be assembled by positioning plural bases 16 side by side or by molding a single base piece provided with an appropriate number of fuse positions.

Plate 18 is secured by screws 46 on the raised area 28 of the base 16. The plate is wider than raised area 28 on the base and is offset thereon and overlies the upper surface 24 of the base. A rectangular aperture 48 is formed in the plate and is aligned with the recess 30. The aperture and the recess are of very nearly the same configuration. The overhanging portion also provides a position of clearance for the ends of the screws 56 which secure blade contact member 211 to the plate 18. A solderless wire connector, of a well known type, is retained on an extension 52 of the plate 18 by a formed end piece 54. in use the circuit wire is secured to the connector. The plate is formed of copper which is advantageously silver plated.

Fuse blade contact member 20 is generally L-shaped and has a foot portion 53 which is mounted on plate 18 transverse the aperture 48 and is positioned above and transverse the recess 30. As seen in FIG. 2, leg 60 extends upwardly from the foot 58 at an angle of approximately Leg 6% has a broad surface 62 which is adapted to engage the complementary flat surface of the knife blade fuse terminal 12. The upper end 64 of the leg is bent outward and cooperates with the bias member 22 to provide a fuse terminal insertion guide means. A stop 66 is formed by lancing a portion of leg 60 above the contact surface 62. The stop 66 engages the fuse terminal 12 (FIG. 2) and fixes its position in the clip 10 relative to the plate 13. Contact member 20 is formed of copper and is advantageously silver plated.

The contact pressure or bias member 22 which is substantially J-shaped is formed of relatively stiff resilient material such as spring steel. It has a long arm 68 and a short arm 70 which are connected by a bight portion 72 of substantially constant radius. The axis of the bight portion, indicated at A in FIGS. 2 and 4, about which the bight may be said to be formed, is perpendicular to the plane in which the coplanar arms 68, 70 lie. Arms 68, 7d are substantially straight but are: slightly inclined inwardly toward one another. The end 74 of the arm 68 is bent outwardly to cooperate with the end 64 of the blade contact 21} to provide insertion guide means for the fuse blade 12.

The fuse terminal clip 10 is assembled in the following manner. Plate 18 with the solderl-ess connector 50 thereon is mounted on the base 16 by screws 46. The I-shaped bias member 22 is placed in the recess 30 in the base 16 through the aperture 48 in the plate with the long arm 68 of the bias member against the end wall 34 of the recess. Arm 68 is positioned substantially perpendicular to the plane of the plate 18 by the wall 34. The bight portion 72 of the bias member is on the bottom wall 40 of the recess and is closely confined laterally by the opposed side walls 36, 38 of the recess. In this position the end 76 of the short arm 70 of bias member 22 extends through the aperture 48 and is slightly above the upper surface of the plate 18.

The blade contact 20 is next secured to the plate 18 by screws 56 with the contact area 62 facing the bias member 22. As noted above, the foot 58 is across the aperture 48 in the plate 18. As the screws 56 are tightened to bring the foot into secure engagement with plate 18, the under surface of the foot pushes down upon the protruding end 76 of the short arm '70. This push causes the bias member to rotate about the axis A of the bight portion 72. The bight portion is restrained against movement in any direction other than pivotal movement about the axis A by the Walls of the recess. The movement of bias member 22 about axis A is sufficient to bring the long arm 63 into engagement with the contact area 62 of the blade contact. Arm 63 engages the contact area 62 before the blade contact 22 is fully seated on plate 18 and continued tightening of the screws 56 stresses bias member 22 by, in effect, forcing the arms 68, 70 apart while the bias member is captive in the base 16. The amount by which the short arm 70 initially protrudes above the surface of plate 18 and the angular relation of the arms 68, 74]) is so proportioned that when the short arm end 76 is flush with the upper surface of plate 18 (FIG. 2) the long arm 68 will be in forceful engagement with the contact area 62.

The knife blade fuse terminal 12 to be inserted in the clip is guided into position by the cooperating portions 64, 74 of the blade contact and the bias member 22. As the terminal 12 is forced therebetween the bias member 22 is further stressed by being deflected away from the contact area 62, thereby increasing the contact pressure between the fuse terminal and the contact area. The fuse blade contact 20 is the principal current carrying member in the clip 10, the contact pressure produced by bias member 22 being evenly distributed over the contact area 62.

In a fuse clip adapted to receive fuses of up to 100 amperes the blade contact 20 is 7/ wide and 70, H.H. copper which is silver plated. The conductor plate is 4 silver plated H.H. copper. The bias member 22 is two inches long overall and is formed from .125" diameter spring steel which has been cadmium plated. The short arm 70 is approximately .715" long and the recess is approximately .560 deep resulting in an initial protrusion of A5" for the end 76 of the short arm.

It will be readily recognized by those skilled in the art that various changes and modifications may be made in the embodiment of the invention disclosed without departing from the spirit and scope of the invention. For example, the aperture 48 in the plate 18 may be omitted and the lower surface of the plate used to engage the end 76 of the short arm 70 to stress the bias member 22 as the plate 18 is secured to the base 16. Where higher currents are to be carried or higher contact pressure is required the proportions of the cooperating parts may be readily changed to produce the desired end results.

I claim:

1. A terminal clip for receiving the knife blade terminal of a fuse, said terminal clip including a bias member having a short arm and a long arm connected by a bight portion of constant radius whose axis of curvature lies between said arms, an insulating base, said base including means for supporting said bias member for limited rotational movement about said axis, a contact member having a fuse terminal engaging portion, said contact member being mounted on said base, means for engaging said bias member for rotating said member about said axis whereby said long arm is urged into engagement with said fuse terminal engaging portion of said contact member.

2. A terminal clip according to claim 1 wherein said fuse terminal engaging portion lies in a given plane and wherein bias member is planar and said planar bias mem- 4 ber is in a plane perpendicular to the plane of said fuse terminal engaging portion and is rotatable in said plane about said axis.

3. A terminal clip for receiving the knife blade terminal of a fuse, said terminal clip including a planar generally J-shaped bias member having a short arm and a long arm connected by a bight portion having a constant radius whose axis of curvature lies between said arms, an insulating base, said base including means for supporting said bias member for limited rotational movement about said axis, a conductor plate mounted on said base, a contact member having a fuse terminal receiving portion and having a foot portion, said foot portion being secured to said conductor plate, said bias member being positioned by said supporting means with the end of the short arm of said bias member engaging said conductor plate whereby said bias member is effectively rotated about said axis and the long arm of said bias member is urged into engagement with the fuse terminal engaging portion of said contact member when said conductor plate is mounted on said base.

4. A terminal clip for receiving the knife blade terminal of a fuse, said terminal clip including a planar generally J-shaped bias member having a short arm and a long arm connected by a bight portion of substantially constant radius whose axis of curvature lies between said arms, an insulating base, said base including means for supporting said bias member for limited rotational movement about said axis, a conductor plate mounted on said base overlying a portion of said supporting means, a contact member having a fuse terminal engaging portion and having a foot portion secured to said conductor plate, said bias member being positioned by said supporting means with the end of the short arm of said J-shaped member engaging said foot portion of said contact member and with the long arm of said J-shaped member in resilient engagement with the fuse terminal engaging portion of said contact member.

5. A terminal clip for receiving a knife blade terminal of a fuse, said terminal clip including an insulating base having an upper surface, a recess formed in said upper surface, said recess being defined by side walls, end Walls and a bottom wall in said base, a conductor plate of a given thickness, said conductor plate being provided with an aperture, a contact member having a fuse terminal receiving portion and a foot portion adapted to be secured to said conductor plate, and a generally J-shaped resilient member having a short arm and a long arm, the length of said short arm being greater than the combined depth of the recess and thickness of said conductor plate, said conductor plate being secured to said insulating base with said aperture aligned with said recess in said base, said resilient member being positioned in the recess in said base and having both arms passing through said aligned aperture, said contact member foot portion being secured to said conductor plate overlying a portion of said aperture, said foot portion of said contact member being in engagement with the end of the short arm of said J-shaped member whereby the J-shaped member is urged downwardly against said bottom wall of said recess and said long arm of said J-shaped member is urged into engagement with the fuse terminal receiving portion of said contact member for receiving said knife blade terminal therebetween in a contact pressure producing relation when said contact member is secured to said conductor plate.

6. A terminal clip for receiving a knife blade terminal of a fuse, said terminal clip including an insulating base provided with a recess, a conductor plate provided with an aperture, a contact member having a fuse terminal engaging portion and having a foot portion adapted to be secured to said conductor plate, and a generally J- shaped resilient member having a short leg and a long leg, said conductor plate being secured to said insulating base with said aperture aligned with said recess, said resilient member being positioned in said recess and having portions of both of said legs passing through said aperture, said contact member foot portion being secured to said conductor plate and overlying a portion of said aperture and being in engagement with the end of the short leg of said J-shaped member whereby the long leg of said J-shaped member is urged into engagement with the fuse terminal receiving portion of said contact member for receiving said knife blade terminal therebetween in contact pressure producing relation when said contact member is secured to said conductor plate.

7. A fuse terminal construction according to claim 6 wherein the I-shaped member has a bight portion of substantially constant radius connecting said short leg and said long leg and wherein said bight portion of said J-shaped member acts as a pivot in said base when the end of said short leg is urged thereagainst by said foot portion of said contact member.

8. A fuse terminal construction according to claim 6 wherein the long arm of said J-shaped member and said contact member have juxtaposed portions which are outwardly divergent with respect to one another to provide fuse terminal guiding means.

9. A fuse terminal clip construction according to claim 6 wherein said contact member is provided with means for limiting the movement of a fuse terminal along said fuse terminal engaging portion, said means including a lanced portion of said contact member.

References Cited by the Examiner UNITED STATES PATENTS 1,551,568 9/1925 Johnson 339262 X 2,709,793 5/1955 Johansson 339-272 X 2,900,618 8/1959 Geier 339272 EDWARD C. ALLEN, Primary Examiner. W. DONALD MILLER, Examiner. 

1. A TERMINAL CLIP FOR RECEIVING THE KNIFE BLADE TERMINAL OF A FUSE, SAID TERMINAL CLIP INCLUDING A BIAS MEMBER HAVING A SHORT ARM AND A LONG ARM CONNECTED BY A BIGHT PORTION OF CONSTANT RADIUS WHOSE AXIS OF CURVATURE LIES BETWEEN SAID ARMS, AN INSULATING BASE, SAID BASE INCLUDING MEANS FOR SUPPORTING SAID BIAS MEMBER FOR LIMITED ROTATTIONAL MOVEMENT ABOUT SAID AXIS, A CONTACT MEMBER HAVING A FUSE TERMINAL ENGAGING PORTION, SAID CONTACT MEMBER BEING MOUNTED ON SAID BASE, MEANS FOR ENGAGING SAID BIAS MEMBER FOR ROTATING SAID MEMBER ABOUT SAID AXIS WHEREBY SAID LONG ARM IS URGED INTO ENGAGEMENT WITH SAID FUSE TERMINAL ENGAGING PORTION OF SAID CONTACT MEMBER. 